diff --git a/xen/arch/arm/include/asm/processor.h b/xen/arch/arm/include/asm/processor.h
index 9e2b6bd597..955cb1a8a7 100644
--- a/xen/arch/arm/include/asm/processor.h
+++ b/xen/arch/arm/include/asm/processor.h
@@ -105,6 +105,7 @@
 #define ARM_CPU_PART_NEOVERSE_V3AE  0xD83
 #define ARM_CPU_PART_NEOVERSE_V3    0xD84
 #define ARM_CPU_PART_CORTEX_X925    0xD85
+#define ARM_CPU_PART_C1_ULTRA       0xD8C
 
 #define MIDR_CORTEX_A12 MIDR_CPU_MODEL(ARM_CPU_IMP_ARM, ARM_CPU_PART_CORTEX_A12)
 #define MIDR_CORTEX_A17 MIDR_CPU_MODEL(ARM_CPU_IMP_ARM, ARM_CPU_PART_CORTEX_A17)
@@ -135,6 +136,7 @@
 #define MIDR_NEOVERSE_V3AE MIDR_CPU_MODEL(ARM_CPU_IMP_ARM, ARM_CPU_PART_NEOVERSE_V3AE)
 #define MIDR_NEOVERSE_V3 MIDR_CPU_MODEL(ARM_CPU_IMP_ARM, ARM_CPU_PART_NEOVERSE_V3)
 #define MIDR_CORTEX_X925 MIDR_CPU_MODEL(ARM_CPU_IMP_ARM, ARM_CPU_PART_CORTEX_X925)
+#define MIDR_C1_ULTRA MIDR_CPU_MODEL(ARM_CPU_IMP_ARM, ARM_CPU_PART_C1_ULTRA)
 
 /* MPIDR Multiprocessor Affinity Register */
 #define _MPIDR_UP           (30)